Claret wrote:Of 75 houses, 48 have a patio. How many houses have a swimming pool?
a. 38 houses have a patio but no swimming pool
b. Number of houses that have a swimming patio and a swimming pool is equal to the number of houses that have neither pool nor patio
Mike's solution is great!
I just wanted to add the general 2-set equation which can be very useful on this type of question:
True # of Objects = (# in group 1) + (# in group 2) + (# in neither group) - (# in both groups)
or
True # = G1 + G2 + neither - both
As Mike applied it to this question:
75 = 48 + pool + neither - both
(1) tells us that "both" = 10 (if 48 have a patio, and 38 have only a patio, then 48-38=10 have both).
So: 75 = 48 + pool + neither - 10
Still 2 variables, can't solve... insufficient.
(2) neither = both, so
75 = 48 + pool + neither - neither
75 = 48 + pool... we can certainly solve for "pool".. sufficient.
(2) is sufficient, (1) isn't... choose (B).
